| Term |
Definition |
| Air dry density (ADD) | Mass (weight) of a timber species expressed in kilograms per cubic metre when the timber’s moisture content is a nominal 12%. |
| Air drying | Process of drying timber by exposing it to natural atmospheric conditions. |
| Arris | Intersection of the face and edge of a piece of wood. |
| Annual rings | Growth rings that form every year during the tree’s growing seasons (see also ‘earlywood’ and ‘latewood’). |
| Backsawn timber | Timber that is sawn so that the growth rings are inclined at less than 45 degrees to the wide face. Sometimes referred to as ‘flat sawn’ or ‘flat cut’. |
| Bark | The corky outer layer of a stem that protects the layers underneath from damage and stops the tree from drying out. |
| Bark pocket | A patch of bark that has become trapped in the wood tissue during the tree’s growth. |
| Baulk | Sawn timber in a large cross-section size, suitable for re-sawing into smaller sizes. Sometimes called ‘flitch’ or ‘junk’. |
| Bending strength | Maximum force that a sample piece of timber can withstand before its fibres rupture – used in the calculation of ‘F grades’. |
| Bird’s eye | Figure in the grain, particularly on backsawn surfaces, where the wood fibres form shapes that look like small eyes. |
| Blackheart | Black or dark brown discolouration occurring in the heartwood of some timbers. |
| Blemish | An imperfection in the appearance of the timber that is not serious enough to be called a ‘defect’. |
| Blue stain | Type of sap stain fungi that lives off the sap in the cell cavities but does not degrade the cell walls or affect the strength of a piece. |
| Borer | Insect that tunnels into wood or bark as a larva (grub) or adult beetle |
| Bound moisture | Moisture which is bound up in the cell walls of wood fibres. Sometimes called ‘combined moisture’. See also ‘fibre saturation point’. |
| Bow | Curve in the lengthwise direction of a piece causing the wide face to move away from a flat plane. |
| Boxed heart | Central heart region of the log contained within the four sides of a sawn piece of timber anywhere within its length. |
| Brown rot | Decay caused by fungi that eat the cellulose fibres, leaving behind a brown residue high in lignin. Sometimes referred to as ‘dry rot’ (although the timber must have at least 20% MC for the decay to live and spread. |
| Brittle | Weakening of the wood fibres that allows them to break or snap easily across the grain. |
| Brittleheart | Abnormally brittle wood fibres in the central heart region of a log, generally caused by growth stresses in the tree or fungal attack in the fibres. |
| Burl | Deformed growth in the wood fibres, often showing as a wart-like outgrowth on the stem, generally resulting from an injury or fungal infection in the growing tree. |